Recently, spectrum around 60 GHz has attracted, e.g., industrial companies and research to explore its potential in wireless communications, short-distance data transfer, and other applications. Phased arrays of antennas may be used to increase antenna gain. A separate phase control may be used to steer the pattern of the antenna to obtain maximum gain.
With the use of planar printed circuit board (PCB) technology, or any other planar, multi-layer substrate technology, antennas are limited in their ability to steer the pattern of the antenna in certain dimensions or in certain directions. For example, using an end-fire array, the emerging radiation pattern will be substantially parallel to the plane of the PCB (e.g., the emerging radiation pattern will “fire off the edge” of the PCB).
One issue encountered with an end-fire antenna is that it cannot easily be integrated into a chip package. To overcome this, a radio frequency (RF) signal (e.g., 60 GHz) must be fed off the chip package and onto the PCB. The dimensions of PCB metallization and vias and typical ball grid array (BGA) pads are larger in many cases than signal transmission lines will allow.